Matching Items (2)
Description

An electric field can be applied to a microfluidic device in order to stop particle flow. Electroosmosis, electrophoresis, and dielectrophoresis act on the particles in different directions in the microfluidic channel, and when these forces create zero net force, the particle stops in the channel. The goal of the performed

An electric field can be applied to a microfluidic device in order to stop particle flow. Electroosmosis, electrophoresis, and dielectrophoresis act on the particles in different directions in the microfluidic channel, and when these forces create zero net force, the particle stops in the channel. The goal of the performed experiments is to investigate whether hydrostatic pressure generated by a syringe pump could help concentrate these particles and separate them from other contents. Introducing precise, adjustable hydrostatic pressure from the syringe pump provides another mechanism for controlling particle behavior. A microfluidic channel was crafted into a device connected to a syringe pump, and videos of 1 µm silica particles in the device were recorded under a microscope in order to show that samples could be infused into the device and concentrated or captured at a specific location in the channel using hydrostatic pressure. Capture of the particles occurred with and without controlled hydrostatic pressure, but these events occurred somewhat consistently at different voltages. In addition, particle movement in the channel with the syringe pump off was originally attributed to the electrokinetic forces. However, when compared to experiments without the syringe pump connected to the device, it became evident that the electrokinetic forces should have moved the particles in the opposite direction and that, in actuality, there is an inherent pressure in the device also affecting particle movement even when the syringe pump is not turned on.

ContributorsRuddle, Kallen (Author) / Hayes, Mark (Thesis director) / Guo, Jia (Committee member) / Hogue, Brenda (Committee member) / Barrett, The Honors College (Contributor) / School of Molecular Sciences (Contributor)
Created2022-12
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Description
Disease prevention and personalized treatment will be impacted by the continued integration of protein biomarkers into medical practice. While there are already numerous biomarkers used clinically, the detection of protein biomarkers among complex matrices remains a challenging problem. One very important strategy for improvements in clinical application of biomarkers is

Disease prevention and personalized treatment will be impacted by the continued integration of protein biomarkers into medical practice. While there are already numerous biomarkers used clinically, the detection of protein biomarkers among complex matrices remains a challenging problem. One very important strategy for improvements in clinical application of biomarkers is separation/preconcentration, impacting the reliability, efficiency and early detection. Electrophoretic exclusion can be used to separate, purify, and concentrate biomarkers. This counterflow gradient technique exploits hydrodynamic flow and electrophoretic forces to exclude, enrich, and separate analytes. The development of this technique has evolved onto an array-based microfluidic platform which offers a greater range of geometries/configurations for optimization and expanded capabilities and applications. Toward this end of expanded capabilities, fundamental studies of subtle changes to the entrance flow and electric field configurations are investigated. Three closely related microfluidic interfaces are modeled, fabricated and tested. A charged fluorescent dye is used as a sensitive and accurate probe to test the concentration variation at these interfaces. Models and experiments focus on visualizing the concentration profile in areas of high temporal dynamics, and show strong qualitative agreement, which suggests the theoretical assessment capabilities can be used to faithfully design novel and more efficient interfaces. Microfluidic electrophoretic separation technique can be combined with electron microscopy as a protein concentration/purification step aiding in sample preparation. The integrated system with grids embedded into the microdevice reduces the amount of time required for sample preparation to less than five minutes. Spatially separated and preconcentrated proteins are transferred directly from an upstream reservoir onto grids. Dilute concentration as low as 0.005 mg/mL can be manipulated to achieve meaningful results. Selective concentration of one protein from a mixture of two proteins is also demonstrated. Electrophoretic exclusion is also used for biomarker applications. Experiments using a single biomarker are conducted to assess the ability of the microdevice for enrichment in central reservoirs. A mixture of two protein biomarkers are performed to evaluate the proficiency of the device for separations capability. Moreover, a battery is able to power the microdevice, which facilitates the future application as a portable device.
ContributorsZhu, Fanyi (Author) / Hayes, Mark (Thesis advisor) / Ros, Alexandra (Committee member) / Buttry, Daniel (Committee member) / Arizona State University (Publisher)
Created2019